Department of Developmental Genetics, Center for Plant Molecular Biology, University of Tübingen, Tübingen, Germany.
Eur J Cell Biol. 2010 Feb-Mar;89(2-3):157-62. doi: 10.1016/j.ejcb.2009.11.021. Epub 2009 Dec 24.
The COP9 signalosome (CSN) is an evolutionarily conserved multiprotein complex with a role in the regulation of cullin-RING type E3 ubiquitin ligases (CRLs). CSN exerts its function on E3 ligases by deconjugating the ubiquitin-related protein NEDD8 from the CRL cullin subunit. Thereby, CSN has an impact on multiple CRL-dependent processes. In recent years, advances have been made in understanding the structural organisation and biochemical function of CSN: Crystal structure analysis and mass spectrometry-assisted studies have come up with first models of the pair-wise and complex interactions of the 8 CSN subunits. Based on the analysis of mutant phenotypes, it can now be taken as an accepted fact that--at least in plants--the major biochemical function of CSN resides in its deneddylation activity, which is mediated by CSN subunit 5 (CSN5). Furthermore, it could be demonstrated that CSN function and deneddylation are required but not essential for CRL-mediated processes, and models for the role of neddylation and deneddylation in controlling CRL activity are emerging. Significant advances have also been made in identifying pathways that are growth restricting in the Arabidopsis csn mutants. Recently it has been shown that a G2 phase arrest, possibly due to genomic instability, restricts growth in Arabidopsis csn mutants. This review provides an update on recent advances in understanding CSN structure and function and summarises the current knowledge on its role in plant development and cell cycle progression.
COP9 信号体（CSN）是一种进化上保守的多蛋白复合物，在调节 Cullin-RING 型 E3 泛素连接酶（CRL）方面发挥作用。CSN 通过从 CRL 的 Cullin 亚基上除去泛素相关蛋白 NEDD8 来发挥其对 E3 连接酶的功能。因此，CSN 对多个 CRL 依赖的过程有影响。近年来，人们在理解 CSN 的结构组织和生化功能方面取得了进展：晶体结构分析和质谱辅助研究提出了 8 个 CSN 亚基的成对和复杂相互作用的第一个模型。基于对突变表型的分析，可以认为--至少在植物中--CSN 的主要生化功能在于其去 NEDDylation 活性，这是由 CSN 亚基 5（CSN5）介导的。此外，还可以证明 CSN 功能和去 NEDDylation 对于 CRL 介导的过程是必需的，但不是必需的，并且出现了关于 NEDDylation 和去 NEDDylation 控制 CRL 活性的作用模型。在鉴定 Arabidopsis csn 突变体中限制生长的途径方面也取得了重大进展。最近表明，G2 期停滞，可能由于基因组不稳定，限制了 Arabidopsis csn 突变体的生长。本文综述了近年来对 CSN 结构和功能的理解的最新进展，并总结了其在植物发育和细胞周期进程中的作用的当前知识。
